Product details


Vs (Min) (V) 4 Vs (Max) (V) 40 Operating temperature range (C) 0 to 70 open-in-new Find other Frequency converters

Package | Pins | Size

PDIP (P) 8 93 mm² 9.81 x 9.43 open-in-new Find other Frequency converters


  • Ensured Linearity 0.01% Maximum
  • Improved Performance in Existing Voltage-to-
    Frequency Conversion Applications
  • Split or Single-Supply Operation
  • Operates on Single 5-V Supply
  • Pulse Output Compatible With All Logic Forms
  • Excellent Temperature Stability: ±50 ppm/°C
  • Low Power Consumption: 15 mW Typical at 5 V
  • Wide Dynamic Range, 100 dB Minimum at 10-kHz
    Full Scale Frequency
  • Wide Range of Full Scale Frequency:
    1 Hz to 100 kHz
  • Low-Cost
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The LMx31 family of voltage-to-frequency converters are ideally suited for use in simple low-cost circuits for analog-to-digital conversion, precision frequency-to-voltage conversion, long-term integration, linear frequency modulation or demodulation, and many other functions. The output when used as a voltage-to-frequency converter is a pulse train at a frequency precisely proportional to the applied input voltage. Thus, it provides all the inherent advantages of the voltage-to-frequency conversion techniques, and is easy to apply in all standard voltage-to-frequency converter applications.

Further, the LMx31A attain a new high level of accuracy versus temperature which could only be attained with expensive voltage-to-frequency modules. Additionally the LMx31 are ideally suited for use in digital systems at low power supply voltages and can provide low-cost analog-to-digital conversion in microprocessor-controlled systems. And, the frequency from a battery-powered voltage-to-frequency converter can be easily channeled through a simple photo isolator to provide isolation against high common-mode levels.

The LMx31 uses a new temperature-compensated band-gap reference circuit, to provide excellent accuracy over the full operating temperature range, at power supplies as low as 4 V. The precision timer circuit has low bias currents without degrading the quick response necessary for 100-kHz voltage-to-frequency conversion. And the output are capable of driving 3 TTL loads, or a high-voltage output up to 40 V, yet is short-circuit-proof against VCC.

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Technical documentation

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Type Title Date
* Data sheet LMx31x Precision Voltage-to-Frequency Converters datasheet (Rev. C) Sep. 29, 2015
Technical article Remembering Bob Pease Jun. 18, 2014
Application note AN-240 Wide-Range Current-to-Frequency Converters (Rev. B) Apr. 29, 2013
Application note Versatile Monolithic V/Fs can Compute as Well as Convert with High Accuracy (Rev. B) Apr. 29, 2013
Application note AN-265 An Electronic Watt-Watt-Hour Meter (Rev. B) Apr. 26, 2013
Application note New Phase-Locked-Loops Have Advangs as Freq to Voltage Cnvrtrs (Rev. B) Apr. 26, 2013
Application note AN-311 Theory and Applications of Logarithmic Amplifiers (Rev. B) Apr. 23, 2013
Application note AN-C V/F Converter ICs Handle Frequency-to-Voltage Needs (Rev. B) Apr. 23, 2013
Application note An Acoustic Transformer Powered Super-High Isolation Amplifier Oct. 04, 2004
Application note 2-Way Multiplexed LCD Drv & Low Cost ADC Using V/F Tech w/COP8 Microcontrollers May 14, 2004
Application note Freq-to-Vltg Converter Uses Sample-and-Hold to Improve Response & Ripple Oct. 03, 2002

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